I don't think we're yet working with a clear understanding of the term "interface." (This proves a bit of a problem, considering "interface" is precisely what we're supposed to be investigating this semester.) Of course, within some specified parameters we should be considering and debating what the notion entails, but we need a firm place to start.

The results of our first project revealed a great deal of variance in impressions — asked to identify an interface, class members pointed to everything from simple tools (eating utensils) to unfiltered environments (parks) as examples. Though there is a sense in which one might call any object of consciousness an "interface" between mind and reality, I don't believe it does us any good to consider "everything" to be interface.

Denise says interface: "refers to the point at which two systems, subjects or organizations meet and interact." She also describes interface as a "condition of contact"between two objects or systems (a somewhat vague indicator — taken from the language of the physical sciences — which probably led to some of our initial "interface-is-everything" confusion).

I know Denise would like our investigations to roam expansively, but I believe we need to set some parameters. Well into our second project, some of us seem to be working with an untenable impression of the concept, in my opinion. Too simple, too inclusive — if the objects and systems we're investigating don’t reveal a consistent position in this regard, we're thwarting our own best intentions.

I want to propose the outlines of a workable, inclusive definition of interface — by way, partially, of considering what interface is NOT. I do have a positive formulation of the notion in mind, but I believe it will be clearer if I get a couple of things out of the way.

1. Interface is not a tool or implement.

A tool, in the simple sense, is an object used to transfer force from one body to another. It has a limited and mechanical function. A fork is a tool for eating; a hammer is a tool for banging. Though a tool lives in the space between a human and the world, its function and possibility is limited by design to yield a particular outcome. (The word "tool" is often used as shorthand for more complex systems — I am referring here to tools as simple physical implements or extensions.) Its orientation is outward — there is nothing about a tool (per se) that indicates the dialogue of between-ness that interface implies.

2. Interface is not a simple mechanism.

We interact daily with a slew of simple machines, from doors with knobs to toothbrushes to coffee grinders. This is where the terrain gets a little muddy, but I believe these simple mechanisms shouldn't qualify as interfaces. Their possibilities of use are limited to particular ends, just as are tools. One may be tempted to say, "I interface with the door by means of its knob," or "I interface with the room through the door." While grammatically correct, perhaps, these propositions do not bolster the sense of "interface" we intend in our design investigations. The outcome of one's interaction with a doorknob can only lead to one result: the door opening (or not). The knob, therefore, is a tool, which is not an interface. The door itself is also more like a tool — it closes off or opens paths through which we may travel, but its function as a barrier or affordance is a direct, unalterable outcome of its design.

The case of the coffee grinder is a bit less clear, but I believe it plays out the same way. The grinder grinds. That is all. "But," one might say, "I can turn a knob and press a button to use it — I can even set a timer and have it grind for me before I wake in the morning." Sure, the grinder could have options, a basic range of functionality. The grinder might have an interface, in fact. But the grinder itself is not an interface. It’s a tool.

3. Interface is not a one-way street.

Even some more complex mechanisms do not qualify as interfaces. Take the gauge or meter, for instance. In its essential functionality, it provides data. It may read pressures or volumes. It may be built from gears and pistons; it may work electronically. It may even have a computerized display. But I do not think the gauge is an interface. No matter how complex of a mechanism it may be, it exists and works to be read. It has one fixed orientation. It only provides information. It faces — it does not interface.

Another example: the telephone. The wired phone is a relatively recent, relatively complex tool. It works to connect two (or more) people via electronic signals that translate, transmit, and manifest audio artifacts. But, essentially, this is all it does. The handset and line functions in a prescribed way — a predetermined manner etched indelibly in its design. Even though the telephone is a miracle of modern technology, it is not an interface, per se. It fits more easily in the class of tool (and interface is not a tool).

Of course, a gauge or a telephone may allow variable input through a number of affordances. A gauge might have some input capacity that allows feedback into the situation being monitored. A rotary phone has a dial with ten numbers that can be spun in any sequence. A touch-tone phone has even more keys. A modern cellular phone may offer everything from traditional phone functionality to internet browsing, GPS, and video. These additional affordances highlight the difference between interfaces and tools. Tools can have interfaces. But tools themselves are not interfaces.

Interfaceisan object or system, existing between two or more things other than itself, which contains within it the possibility of a change in the conditions of contact between the other things.

Let me try to unpack this a little.

First, since an interface exists between two or more other things, it must in a sense be passed through by those other things in order to afford the change in conditions of contact I believe are requisite to its being. Its being is supported by its facilitation of responsive interaction. It is, in a sense, a membrane. But it is not passive — it facilitates a certain kind of change as it is passed-through.

This in-between state implies that each of the objects associated with an interface is able, in some way, to affect the dynamic of the relationship built around and supported by the interface. This affect-ability does not imply a volitional consciousness on each side, however. It simply means that the information an object, thing, or person receives through an interface on one side is related to the state of being of that which is on the other side. I’ll say more about this.

Consider, for instance, a user of a computerized catalog in process of searching an archive for a particular book. The interface here is the catalog, designed to function in between the user and the archive — two things that are not interfaces, per se. What passes through the interface from the user’s side is the manifestation of her intent: computer code specifying search terms. On the side of the archive, there is no conscious mind or intent, to be sure, but there is a huge collection of data that will be mined, reconfigured, and sorted by the interface in order to show something particular to the user. The search input results in a particular bit of data being passed from the archive through the membrane of the interface to the user. If it is the bit of data the user wanted, she is done searching. Thus the interface has supported on one side a change in condition of the user (aspirant to searcher to satisfied finder) and on the other side a change in condition of the data (which was sorted and read, made legible in a particular way by the interface).

It is easy to see how an interface can facilitate a change in the conditions of contact of a volitional, conscious user. It is not as clear what we mean by a "change in the conditions of contact" when we consider non-conscious objects, systems or data on the other side. I think I can explain this, however.

Things appear to us in limited ways. The shape of our human consciousness (which is particularly situated in certain spatial and temporal relationships) restricts our perspectives on the matters and structures of the reality that surrounds us. We can only apprehend certain views of our reality — a reality comprised by these objects of consciousness — at any given moment. Other views might be given in time, or with a shift in perspective. But other views still are inaccessible without technological assistance, and some views are permanently cordoned off. In terms of our awareness, things are limited to what they appear to be. So, it is precisely the revealing of new vantages on the objects of consciousness through an interface that heralds a change in condition of those objects for us. Interface affords us new experiences of a new world that could not exist without it — this is why we may speak of a "change in the conditions of contact" of that which we apprehend through an interface. We see things differently through an interface because they are, in fact, made different by the interface.

The interface contains within itself the possibility of a change in the conditions of contact of those things which pass through it.

* * * * *

Interface is a bit of a slippery notion, but I believe it points clearly to a certain kind of thing in a certain kind of scenario. When we call something an interface, we’re speaking not only to the thing itself but also to its relationships with the other stuff it exists between. It’s important for us to understand the complexity of the notion in order that we can target our investigations with informed intent. The dynamic manifest around and through an interface is ripe for interrogation, and I think we should start here.